Guidelines for New Foundation Design - High Water Table or Surface-Perched Water

School Construction Authority Architecture & Engineering

Design Requirements Structural - Section 3.0

Requirement Applies to: New Construction Major Modernizations Capital Improvement Projects

(Rev. 3 – 03/30/12) 3.1.1 – Guidelines for New Foundation Design - High Water Table or Surface/Perched Water Page 1 of 2

3.1 Design 3.1.1 Guidelines for New Foundation Design - High Water Table or Surface/Perched Water

Description/Design Approach:

1. Foundations are to be designed to take into account water conditions at the subject site. Such conditions may arise due to a high water table or from inundation from a perched or surface water condition. In order to ensure that any such conditions are adequately addressed, a dedicated meeting is to be held by the design team and the SCA structural managers on every capacity project to discuss the geotechnical findings and the site data to determine the appropriate level of water resistant design.

2. To protect the building from water infiltration due to high water table, including potential

current and future fluctuations in the water table and to minimize hydrostatic pressure on the foundation, raise the building elevation where feasible,

3. Where the foundation may be subject to a perched water or surface water condition,

detailing of structure shall be such to prevent intrusion of water into building. This may entail detailing the project to include full waterproofing, or upgrading the environmental vapor barrier system typically installed on new capacity projects to a more water resistant system.

4. Where design ground water levels will be above basement slabs, the architect/engineer shall

prepare cost estimates for the following foundation alternatives. Alternatives should also look at the construction methods that will be employed to ensure their feasibility:

a. Make basement slab thick enough to counteract the uplift pressure. b. Design reinforced concrete slabs that are tied into the footings, walls and columns, such that

the overall weight of the structure is utilized in resisting the uplift forces, or employ the use of tie downs, if feasible.

5. Structures are to be designed for hydrostatic pressure and waterproofed for a design water

table elevation five feet above the highest level given on the borings, as a minimum. The intent to account for the effects of normal cyclical rising and falling of the water table as well as long term rising of the water table. The geotechnical engineer is to study the historic data for the area, make an analysis and determine if the design ground water elevation needs to be greater than five feet above the highest actual shown on the borings.

Refer to DR 3.2.2 for guidelines for Foundation and Slab design.

6. The preferred method of waterproofing is a positive-side waterproofing applied to the outside

surfaces of foundation walls and slabs. Utilities are to be designed such that they run within the building space (preferred) or are encased and placed above the waterproofing to avoid penetrations in the waterproofing to the greatest extent possible. Provide waterstop at all joints.

Waterproofing materials for walls and floors are specified in the Specification Section 07115, which meet the accepted material requirements of BC 1807.




(Rev. 3 – 03/30/12) 3.1.1 – Guidelines for New Foundation Design - High Water Table or Surface/Perched Water Page 2 of 2

7. Where dewatering is likely to be required during construction activities for the foundation

system, the geotechnical engineer shall determine the estimated pumping rates required. The I&EH Department is to be consulted to determine if the ground water is safe to be disposed of in the sewers and if there is potential of bringing in contaminants to the site based on the estimated pumping rate. The capacity of the local sewers shall be evaluated to determine if the dewatering rate and disposal falls within DEP allowable range for temporary dewatering and the possible need for off-site disposal. The result of these studies is to be discussed with Construction Management and I&EH to determine what is to be included in the bid documents, which will typically involve incorporating items in Section 02200.




(Rev. 2 – 07/01/09) 3.1.2 – Design Live Loads Page 1 of 1

3.1 Design 3.1.2 Design Live Loads

Description/Design Approach: Live loads used in design shall be as per the 2008 NYC Building Code required by Table 1607.1 (minimum), except as modified by the following table. Due to the possibility of change in the use of various areas in a school building and the increase of the student population in the future, live-load reduction as allowed by the Building Code is not to be used, except as approved by the Authority for unusual cases. Structural elements shall be designed to support the uniformly distributed live load or the concentrated load, whichever produces the greater load effect.

Use Area Design Live Load LL (PSF)

Kitchen Areas* 150****

Mechanical Spaces** 75

Roofs with water retention*** 45 or R=5.2(ds+dr)... [see EQ. 16-37] whichever is greater

Toilet Rooms 60****

The uniform distributed design live load for each floor and the equivalent uniform partition loads or actual partition load shall be tabulated and shown on the drawings. Note that the live load in school corridors above the first floor is 80 psf.

_________________________________________________________________________ * The indicated live load includes most equipment loads. If a piece of equipment is in excess of

this, such as the walk-in freezer, the design load shall be that of the equipment for that area. This loading shall be mapped on the floor plan.

** If a piece of equipment is in excess of this indicated live load, the design load shall be that of the

equipment for that area. This loading shall be mapped on the floor plan.

*** This live load is only to be used for roofs subject to roof detention, and may be sufficient to account for some equipment loads supported on enclosed curbs weighing less than the live load. If a piece of equipment is in excess of this indicated live load, the design load shall be that of the equipment for that area.

**** ASCE Standard 7-02, Table C4-1




(Rev. 5 – 07/01/09) 3.1.3 – Seismic Design Criteria Page 1 of 2

3.1 Design 3.1.3 Seismic Design Criteria


New school buildings and additions shall be designed and constructed to resist the effect of earthquake motions as prescribed in BC 1614, which is in accordance with the provisions of Sections 9.1 through 9.6, 9.13 and 9.14 of ASCE 7-02. New school buildings and additions are assigned to Seismic Use Group II and a corresponding Occupancy Category III with occupancy importance factor IE = 1.25. The site class shall be determined in accordance with BC 1615.1.1. The site specific procedure of Section 1615.2 shall be used for structures on sites classified as Site Class F, in accordance with Section 1615.1.1. Each structure shall be assigned to a seismic design category in accordance with BC1616.3. Seismic design categories are used to determine permissible structural systems, limitation on heights and irregularity, and the types of lateral force analysis that must be preformed. All structures shall be separated from adjacent structures as prescribed in BC 1617.3.2. Structural separation refers to the property line, not to adjacent property. When a structure adjoins a property line, that structure shall be set back from the property line by at least 1 inch for each 50 feet of height. For structures in Seismic Design Category D, refer to Section 1620.4.5 for additional requirements.

Refer to BC 1617.6.1.2 for design requirements for structures having a flexible upper portion supported on a rigid lower portion. Existing structures and alterations to existing structures need to comply with the provisions of seismic design only when required by Sections 9.1.2.2 and 9.1.2.3 of ASCE 7-02. Section 9.1.2.2 indicates any addition that is structurally independent from an existing structure shall be designed and constructed in accordance with the seismic requirements for new structures. When an addition is not structurally independent from an existing structure, it shall be designed and constructed such that the entire structure conforms to the seismic force resistance requirements for new structures unless all three of the following conditions are complied with: 1. The addition shall comply with the requirements for new structures. 2. The addition shall not increase the seismic forces in any structural element of the existing

structure by more than 5% unless the capacity of the element subject to the increased forces is still in compliance with these provisions.

3. The addition shall not decrease the seismic resistance of any structural element of the existing

structure unless the reduced resistance is equal to or greater than that required for new structures.

Section 9.1.2.3 indicates that when a change of use results in a structure being reclassified to a higher Seismic Use Group, the structure shall comply with the seismic requirements for new construction. For exceptions, refer to 9.1.2.3 of the ASCE 7-02. The following information related to seismic loads shall be shown on the drawings:




(Rev. 5 – 07/01/09) 3.1.3 – Seismic Design Criteria Page 2 of 2

1. Seismic importance factor IE and seismic use group. 2. Mapped spectral response acceleration SS = 0.365g and S1 = 0.071g 3. Site class 4. Spectral response accelerations coefficient SDS and SD1 5. Seismic design category 6. Basic seismic force resisting system 7. Design base shear 8. Seismic response coefficient CS 9. Response modification factor R 10. Analysis procedure used




(Rev. 2 – 07/01/09) 3.1.4 – Vibration Criteria For Floor Construction Page 1 of 1

3.1 Design 3.1.4 Vibration Criteria for Floor Construction


A vibration analysis is to be performed to determine the sensitivity of the floor construction to motion. The design criteria for vibration shall be to limit the motion to within acceptable standards set in the AISC Steel Design Guide Series #11. This study must show compliance with all criteria for controlling annoying floor movement in all spaces in the building that are affected by walking excitation (such as classrooms and offices adjacent to a corridor) or rhythmic excitation as typically occurs in a gymnasium and/or an auditorium stage area. The analysis must also verify that there is no potential for a resonance condition. In compliance with Design Requirement 3.3.1, a vibration analysis is required to be submitted along with each proposed framing layout indicating their adequacy against all walking and/or rhythmic excitations. Mechanical equipment that can produce objectionable vibrations in any portion of structure utilized by students and staff shall be isolated to minimize the transmission of such vibrations to the structure in accordance with ASCE 7-02 B.1.3. Also, use the service of an acoustical consultant to investigate and make recommendation for induced vibrations/noise on the structure from exterior sources such as trains.




(Rev. 2 - 03/30/12) 3.2.1 – Waterproofing System For Foundations Page 1 of 1

3.2 Foundations 3.2.1 Waterproofing Systems for Foundations

Description/Design Approach: 1. The preferred method of waterproofing for buildings subject to hydrostatic pressure is by

positive-side application, consisting of a sheet membrane waterproofing system. The membrane shall extend up the entire height of the wall to just below the grade. Provide a mud-mat working surface to facilitate installation of the waterproofing at horizontal applications. Refer to Specification Section 07115 for materials, which meet the accepted material requirements of BC 1807. As the system must typically also act as an environmental barrier, the waterproofing details and specifications are to be given to the I&EH department to review to verify the system design is also sufficient to act as an environmental barrier.

2. All foundation construction joints (walls, slabs, etc) regardless of water conditions are

to have a gasket type waterstop as a minimum and these shall be shown on the drawings. For habitable spaces (those occupied by other than maintenance personnel) subject to hydrostatic pressure, provide acrylate ester injectible hose-type waterstop system for all construction joints that are within the water table.

3. Where the building is situated such that the main portion of the building is not in the

potential water table zone but deeper pits (elevator, mechanical, etc) are, a combination waterproofing and environmental barrier system by the environmental barrier manufacturer may be accepted in lieu of a full membrane waterproofing. All tie-in and overlaps between materials must be verified as compatible by the manufacturers of those materials.

4. Depending on the potential for infiltration from perched or surface water, the design

team and A&E staff shall determine if waterproofing membranes or upgraded environmental barrier systems are to be used. A meeting is to be held by the 60% Construction Document specifically to review the geotechnical report and potential issues.

5. Surfaces subject to constant water, such as sump pits, are to have a waterproofing

application consisting of a “crystalline” type waterproofing on the interior side. This is in addition to the positive side application required for high water table.




(Rev. 3 - 03/30/12) 3.2.2 – Guidelines For Foundation And Slab Design Page 1 of 3

3.2 Foundations 3.2.2 Guidelines for Foundation and Slab Design


The building superstructure is to bear on cast-in-place concrete foundations, either footings or pile caps, with concrete walls or grade beams supporting exterior walls and retaining earth. The foundation design, including the method of support for utilities, is to be based on the recommendations of a geotechnical engineer. Exterior foundation wall and slab protection treatment is based on the existing soil/water conditions and SCA technical requirements. For all conditions, provide a drainage panel on the exterior of all walls to the bottom of footing to reduce build-up of hydrostatic pressure from saturated soils. Where not subject to hydrostatic pressure, provide perforated pipe at the footing level connected to the storm system or a drywell system by gravity if the existing soil at the footing level is of low permeability. Provide membrane systems as follows: a. High Water Table/Perched Water Condition: Where the building is subject to hydrostatic

head, follow DR 3.1.1, Guidelines for New Foundation Design - High Water Table or Surface/Perched Water. If the geotechnical investigation reveals the potential for perched water, the condition must be carefully studied and the design of the structure may need to be treated as a high water table condition, which could also impact the SSDS system. If there is potential for transient water to be on the site, discuss with A&E the need to upgrade the environmental barrier to a thicker placement or potentially a membrane waterproofing installation. Refer to DR 3.1.1.

b. SSDS System: For projects requiring a sub-slab depressurization system with an

environmental barrier on the walls and slabs and waterproofing is not needed, the IEH department will recommend the membrane system to be utilized and provide the design documents. Careful coordination is required if both an environmental and a separate waterproof membrane are to be installed at different sections of the foundation system; in such cases the interface of the two membranes must be approved by the material manufacturers to avoid a design where two adjoining materials are incompatible. Such interfaces are to be avoided. Provide gasket type waterstops at all joints in slab and walls.

c. All other cases: Where there is no requirement for an environmental membrane on the

foundation wall, utilize a sheet membrane waterproofing installed to below the slab level, typically to 1 foot below the top of footing. Regardless of water level, provide gasket type waterstops at all joints in the slabs and walls. Refer to Specification Section 07115 for materials, which meet the accepted material requirements of BC 1807.

Refer to BC 1805.1 through 1805.9 for foundation design and construction requirements. Foundation walls shall be designed to support the weight of the full hydrostatic pressure of un-drained backfill unless a drainage system is installed in accordance with BC 1807.4.2 and 187.4.3. See BC 1910 for additional requirements for footings and foundations of structures assigned to Seismic Design Category C or D.





Where a structure is assigned to Seismic Design Category D in accordance with BC1616, individual spread footings founded on soil defined in BC1615.1.1 as Site Class E or F shall be interconnected by ties. Refer to BC 1805.4.2.2 for seismic ties design requirements. Where a structure is assigned to Seismic Design Category C in accordance with Section 1616, individual pile caps, piers shall be interconnected by ties. Refer to BC 1808.2.23.1 for seismic ties design requirements. Refer to BC 1808.2.23.2 for seismic design requirements for structures that are assigned to be of Seismic Design Category D and are supported on Pier and Pile Foundations. For design of the foundation walls, perform a comparison of the cost effectiveness of a deep-grade beam versus walls with continuous footings. Since the footings should rest on a suitable soil, some of the wall footings may become very deep requiring additional excavation. In this case, it may be more economical if the walls are supported by piers at the location of the columns footings or pile caps. The decision to support slabs resting on grade structurally or to have the slab supported solely by the soil is to be based on the geotechnical report. Slabs on grade are to be designed, with the following minimum requirements: 1. Non-structurally supported slabs-on-grade:

a. Basement/Cellar slabs are to be five inches minimum with a minimum reinforcement of

6x6-W2.9xW2.9 welded wire fabric, placed 1” from the surface. The reinforcement and thickness are to be increased if required by design considerations. The slab shall bear on a vapor barrier and 6” crushed stone base. Provide additional reinforcement at reentrant corners and joints as required to minimize cracking. Thicken slab at all masonry partitions.

b. Pipe & Duct and Crawl space slabs are to be 3½” minimum with a minimum of 6x6-

W2.9xW2.9 welded wire fabric. The slab shall bear on a vapor retarder and 4” crushed stone base. Provide additional reinforcement at reentrant corners and joints as required to minimize cracking.

2. Structurally supported slabs-on-grade Slabs are to be of thickness and reinforcement as required by design considerations, with the

minimum reinforcement following recommendations of ACI 318. Bottom reinforcement is to have 2” clear minimum from grade and top reinforcement 1” clear from top of slab. The slab shall bear on a vapor barrier and 6” minimum of crushed stone base. Provide additional reinforcement at reentrant corners as required to minimize cracking.

When provided for the project, Foundation Drawings shall refer to the Environmental Drawings provided by the I&EH department that clearly details the passive/active vapor barrier/venting system on the Drawings. The foundation sections shall be coordinated such that the design facilitates the installation of the systems. If the areas that require backfilling are narrow and will be difficult to provide proper compaction, specify backfilling with crushed stone and proofrolling.





Obtain utility company design requirements for vaults after providing the utility company with all required geotechnical data so the design can be incorporated into the Contract Documents. The designer and geotechnical engineer are to investigate the protection of adjacent properties and structures, as well as those of the school property, to ensure that a feasible scheme is possible. While the Contractor is responsible for the final design of the underpinning/shoring/bracing scheme and for filing such, a schematic scheme is to be indicated on the Drawings with adequate notes to ensure the Contractor is aware of all issues to be considered. As an example, if due to site restrictions on adjoining properties, the adjoining property cannot be excavated or accessed; or shoring can be only installed on the lot line, the Contract Documents must be clear to show the foundation is integrated into the shoring scheme. Also, schematic underpinning sections should state bracing is required if the height of such underpinning required by the project would be impractical without it and fail.




(Rev. 2 - 07/01/09) 3.2.3 – Concrete Reinforcement Page 1 of 1

3.2 Foundations 3.2.3 Concrete Reinforcement


Reinforcing bars are to conform to the requirements of ASTM A615, Grade 60, unless higher strength bars are needed by design considerations. Wire mesh shall conform to ASTM A185. Reinforcement to be welded shall conform to the requirements of ASTM A706. Reinforcement for concrete exposed to the elements, such as exterior framed slabs, exposed face of retaining walls, parapet concrete back up, curbs, etc. are to be epoxy coated or galvanized.




(Rev. 1 - 04/15/05) 3.3.1 – Economic Analysis Of Structural Framing System Page 1 of 1

3.3 Superstructure

3.3.1 Economic Analysis of Structural Framing Systems

Description/Design Approach: 1. As part of the schematic design submittal, the Structural Engineer shall propose and submit

alternative steel framing layouts for a typical bay as well as for a long span bay, with discussion as to which layout is the most economical. The vibration analysis of each layout should also be submitted indicating the adequacy against walking and/or rhythmic excitations. In addition, the proposed location of the lateral load-resisting frames is to be indicated on the plans for each scheme.

2. As part of the preliminary submission, provide examination of alternative methods for supporting of

exterior masonry. This is to avoid the need for diagonal struts to brace the wall/lintel assembly. 3. If a reinforced concrete structure is being considered, a full economic analysis must be performed

to justify the costs. As part of the Schematic design submittal, the Architect/ Engineer shall submit cost analyses for a typical bay including a column cost (in $/S.F.), for a concrete and a steel framed structure as well as any increased cost for the foundation. Include the limited reuse of formwork in the concrete alternative.




(Rev. 6 – 07/01/09) 3.3.2 – Structural Floor And Framing System Page 1 of 2

3.3 Superstructure 3.3.2 Structural Floor and Framing Systems


Depending on compatibility with architectural and engineering requirements including vibration, the structural floor system shall be a 61/4-inch composite slab consisting of 3” galvanized metal decking with 31/4" lightweight structural concrete topping to be supported on composite structural steel beams framing into steel columns. The designer shall include in the design an additional 1” to 1.5” of concrete to account for beam and deck deflections in both the steel design and design of the deck. Designer should specify the grade (minimum yield strength) of the deck and modify the specifications and drawings accordingly. Gage of metal deck shall be sufficient to sustain the wet-concrete weight and construction loads without shoring. Where small depressions are required, reducing the deck to 2” in depth should be investigated in lieu of depressing the entire slab-deck assembly. If the spacing of the filler beams allows and/or the height of the building can be reduced, the use of 2” in lieu of 3” metal deck should be considered. In compliance with Design Requirement 3.3.1, a vibration analysis is required to be submitted along with each proposed steel framing layout indicating their adequacy against walking and/or rhythmic excitations. The framing is to be designed such as to reduce the steel piece count and tonnage to the greatest extent possible while complying with serviceability and vibration requirements. The spacing of the filler beams should be within the 10’+ range in order to utilize a three-span condition for the deck. Where the building configuration is such that the steel cannot be reasonably spaced to that criteria, the deck may span for 12’+ provided the deflection on a two-span condition does not exceed the manufacturer’s recommended limits. The proposed layout shall be discussed with the A&E structural unit, with back-up information or calculations to indicate adequacy for review and acceptance. Refer to DR 3.3.1 for requirements for alternate framing schemes. Where the metal-deck layout requires the use of a single-span, shoring should be indicated if the use of a thicker deck would have adverse cost effect or would negatively affect the progress of the construction work. Buildings and other structures, including the main wind force resisting system and all components and cladding, shall be designed in accordance with requirements of the BC 1609. Also, every structure and portion thereof shall be designed and constructed to resist the effects of earthquake motions as required in BC 1614. Braced frames shall be provided for seismic and wind resistance; locations shall be coordinated with the architecture of the building. The maximum floor-to-floor drift due to wind loads is limited to 1/400 of the floor-to-floor height. The drift due to seismic loads shall be as per the building code. Structural lateral and vertical force resisting systems utilized for the project shall be indicated on construction documents, with clear indication of the design load which govern. Structural-steel members shall be Grade 50 steel conforming to ASTM A992. The use of open web joists for floor framing is not permitted. The camber to be indicated on the drawings is to be 2/3 of the pre-composite dead load deflection to account for the inherent stiffness of the structural connections. The camber for members between columns or between columns and girders may be somewhat less due to greater resistance to movement by these more rigid elements. As per AISC recommendation, cambers less than ¾” are not to be specified; thus, a larger size beam might be more economical to control the deflection.




(Rev. 6 – 07/01/09) 3.3.2 – Structural Floor And Framing System Page 2 of 2

While columns, beams and other structural members customarily shall have sprayed fireproofing, the standard metal deck system is to meet the required fire classification rating without added fire protection to the underside of the metal deck. Areas with higher fire-resistance rating may have sprayed fireproofing applied to the deck. Only cementitious sprayed fireproofing shall be used to provide fireproofing of steel beams, columns, and deck. For specific areas exposed to public view where the regular cementitious sprayed fireproofing is not appropriate, a decorative acoustic sprayed fireproofing or intumescent fireproofing is to be used. The structural floor framing systems shall be capable of sustaining the superimposed loads with a maximum deflection of L/360. Structural systems that directly or indirectly brace or support masonry shall be capable of sustaining the masonry and live loads with a maximum deflection of L/600.

The following code requirements shall be evaluated and implemented where applicable:

1. Structures carrying live load which induce impact shall include allowance in

accordance with BC 1607.8. 2. Refer to BC 1608.10 for thermal forces consideration in structural design. 3. All structures shall be designed to satisfy Structural Integrity Requirements of the BC

1625. 4. Structural columns that are directly exposed to vehicular traffic shall be designed for

vehicular impact based on requirements of the BC 1625.5. 5. In buildings with gas piping operating at pressures in excess of 15 psi, all key elements

and their connections shall be designed to resist a potential gas explosion, in accordance with requirements of the BC 1625.6.

Refer to BC 1603.1.1 through 1603.1.7 for design loads and other information related to structural design, which shall be indicated on the construction documents.




(Rev. 6 – 07/01/09) 3.3.3 – Structural Framing Systems For Roof Areas Page 1 of 2

3.3 Superstructure 3.3.3 Structural Framing Systems for Roof Areas


Depending on compatibility with architectural and engineering requirements, the structural roof system shall be a minimum 61/4-inch composite slab consisting of 3” galvanized metal decking with 31/4" lightweight structural concrete topping supported on composite structural steel beams framing into steel columns. The designer shall include in the design an additional 1” to 1.5” of concrete to account for beam and deck deflections in both the steel design and design of the deck. Designer should specify the grade (minimum yield strength) of the deck and modify the specifications and drawings accordingly. Gage of metal deck shall be sufficient to sustain the wet-concrete weight and construction loads without shoring. If the spacing of the filler beams allows and/or the height of the building can be reduced, the use of 2” in lieu of 3” metal deck should be considered. Pitching of the roof is to be achieved by sloping the steel-farming members, thereby minimizing the amount of concrete fill required. The framing is to be designed such as to reduce the steel piece count and tonnage to the greatest extent possible while complying with all serviceability requirements. The spacing of the filler beams should be within the 10’+ range in order to utilize a three-span condition for the deck. Where the building configuration is such that he steel cannot be reasonably spaced to that criteria, the deck may span for 12’+ provided the deflection on a two-span condition does not exceed the manufacturer’s recommended limits. The proposed layout shall be discussed with the A&E structural unit, with back-up information or calculations to indicate adequacy for review and acceptance. Refer to DR 3.3.1 for requirements for alternate framing schemes. Where the metal-deck layout requires the use of a single-span, shoring should be indicated if the use of a thicker deck would have adverse cost effect or would negatively affect the progress of the construction work. The camber to be indicated on the drawings is to be 2/3 of the pre-composite dead load deflection to account for the inherent stiffness of the structural connections. The camber for members between columns or between columns and girders is to be somewhat less due to greater resistance to movement by these more rigid elements. As per AISC recommendation, cambers less than ¾” are not to be specified; thus, a larger size beam might be more economical to control the deflection. Steel roof deck without concrete is acceptable for barrel roof type construction. Ensure that adequate details for attaching hung ceilings are provided. While columns, beams and other structural members customarily shall have sprayed fireproofing, the standard metal deck system is to meet the required fire classification rating without added fire protection to the underside of the metal deck. Areas with higher fire-resistance rating may have sprayed fireproofing applied to the deck. Only cementitious fireproofing shall be used to provide fireproofing of steel beams, columns, and deck. For specific areas exposed to public view where the regular cementitious sprayed fireproofing is not appropriate, a decorative acoustic sprayed fireproofing or intumescent fireproofing is to be used. Structural steel members shall be Grade 50 steel conforming to ASTM A992. The use of open web joists is permitted for roofs not requiring a fire-resistance rating.




(Rev. 6 – 07/01/09) 3.3.3 – Structural Framing Systems For Roof Areas Page 2 of 2

The roof framing systems shall be capable of sustaining the superimposed loads with a maximum deflection of L/240. Structural systems that directly or indirectly brace or support masonry shall be capable of sustaining the masonry and live loads with a maximum deflection of L/600. Refer to BC 1607.11, BC 1608 and BC 1611 for roof loads design requirements.




(Rev. 2 - 07/01/09) 3.3.4 – Exterior Masonry Support Systems Page 1 of 4

3.3 Superstructure 3.3.4 Exterior Masonry Support Systems


Provide relieving angles at each story height. For single multi-story spaces such as gymnasiums, supports may be provided from foundation wall up to 30 feet maximum. The design and detailing for these multiple story conditions is to be engineered to ensure masonry will not crack. For walls with intermittent windows, provide a relieving angle supported at the floor level from wedge inserts cast in the floor slab. Provide a hung lintel assembly or bond beam system over the windows openings. The attached conceptual sketches provide a general guide of possible detailing. Actual conditions may allow simpler and less expensive designs depending on geometry of the construction. For walls with the majority of the length being windows, provide a continuous hung lintel support system. Hung lintel assembly is to be designed such to avoid where possible the need for diagonal struts to brace the wall/lintel assembly. Where the structural steel beam or wall is required to be fire protected, the steel lintel or relieving angle is required to be fire protected when openings or spans are over 4’-0” wide, except for the leg support of the outer face of masonry that is supported by fire protected inner members that support the full load (BC 714.2, BC 714.6). Per BC 714.6 exception 1, the members of an assembled metal lintel assembly that support only outer face masonry that is securely bonded or anchored to backing need not be fire protected, provided that the inner members of the assembly support the full load imposed. For design purposes, lintels are to span no more than 4’-0” and the face of the hanger exposed to the cavity is not to have fireproofing to facilitate the installation of the vapor barrier and insulation, as allowed per exception 1.

Relevant Conceptual Sketches: 1. Typical Edge of Slab Detail at Relieving Angle Sketch SK1 dated 7/01/09.

2. Lintel Assembly at Wall Opening Sketch SK2 dated 7/01/09. 3. Lintel Assembly at Wall Opening Sketch SK3 dated 7/01/09.











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